Koji Tani

A new technique for 3D dynamic finite element analysis of electromagnetic problems with relative movement

In the new technique, the meshes of the stationary part and the moving part are prepared independently. The new technique couples them with the help of Delaunays method at each position of the moving part. The results demonstrate that the new approach is suitable for the solution of electromagnetic problems with relative movement.

Thin film write head field analysis using a benchmark problem

A benchmark problem has been proposed by the Storage Research Consortium (SRC) in Japan, for evaluating the applicability of computer codes to 3-D nonlinear eddy current analysis of thin film magnetic recording write head. Various codes using the finite element method are compared in terms of the write head field and the computational efficiency. The difficulty in 3-D mesh generation of thin film head is also discussed. The write head fields calculated by various codes using different meshes show fairly good agreement. The calculated write head fields are verified by measurement using a stroboscopic electron beam tomography. It is found that the calculation time strongly depends on unknown variables.

H-version adaptive finite element method using edge element for 3D non-linear magnetostatic problems

The h-version adaptive finite element method employing edge elements for 3D non-linear magnetostatic problems is presented. Two different techniques for the mesh refinement procedure are performed. One is to reconstruct a new mesh using the Delaunay method and the other is to subdivide elements into 2, 4 or 8 tetrahedral elements. The error estimation method proposed by Zienkiewich and Zhu (1987) is applied to the edge element code. The TEAM Workshop Problem 20 is calculated using two techniques, and the results confirm the efficiency of the presented approaches.

Error estimation for transient finite element method using edge elements

This paper is concerned with the error estimation procedures for the transient finite element method using edge elements. The local error is estimated by the continuity of the tangential component of the magnetic field strength and the eddy currents on the element boundaries. The transient finite element analyses of a thin film write head are performed using two meshes of different sizes and the error estimator is applied to the solutions obtained. The results show the efficiency of our error estimation procedures and the importance of the mesh refinement.

Dynamic analysis of linear actuator taking into account eddy currents using finite element method and 3-D mesh coupling method

The dynamic analysis of a linear actuator, taking into account eddy currents using the finite element method (FEM) and a 3-D mesh coupling method, is presented. The finite element mesh is constructed using the 3-D mesh coupling method at each position of the actuator. After the mesh coupling, the magnetic field analysis is performed. Since the mesh of the actuator, which has conductivity, is not changed by the mesh coupling, the transient FEM is directly applicable to the problem. Computed results confirm the efficiency of this method.

Parallel Performance of Multithreaded ICCG Solver Based on Algebraic Block Multicolor Ordering in Finite Element Electromagnetic Field Analyses

We present a parallel multithreaded incomplete Cholesky-conjugate gradient (ICCG) solver for a linear system derived from a finite element electromagnetic field analysis. Algebraic block multicolor ordering is introduced to parallelize the solver with a high cache hit ratio and convergence comparable to the sequential solver. We develop the parallel ICCG solver based on reordering with modification for electromagnetic field analyses involving external circuits. The numerical results from practical models show that a 2.6- to 3.8-fold speedup compared with the sequential solver is attained using eight cores.

Finite element analysis of AC losses in double helix superconducting cables

To calculate AC losses of double helix superconductors, we have employed the power law current-voltage characteristics model and the A-/spl phi/ method in the conductor region in conjunction with the finite element method using edge elements. By comparing the double helix model to three other geometrical configurations, the winding effect of the AC losses of superconducting cables is investigated.

Transient finite element method using edge elements for moving conductor

A transient finite element method using edge elements for moving conductors is presented. Here, the magnetic vector potential is interpolated at the upwind position and the time derivative term is discretized by the backward difference method. As a result, the system matrix becomes symmetric and the ICCG method is applicable to solve the matrix. This method is used to solve an eddy current rail brake system. The results demonstrate that this approach is suitable to solve transient problems involving movement.

Dynamic analysis of linear oscillatory actuator driven by voltage source using FEM with edge elements and 3-D mesh coupling method

A dynamic analysis of linear oscillatory actuator driven by a voltage source using the finite element method with edge elements and 3-D mesh coupling method is presented. At each position of the plunger, the finite element mesh is automatically constructed using a 3-D mesh coupling method. After the mesh coupling, the magnetic field analysis is performed. The computed results are in good agreement with the measurement, showing the efficiency of our approach.